Field of the Invention
The present invention relates to a vibration drive device (vibration actuator) that brings a vibrating body and a driven body into pressure contact with each other and causes the vibrating body and the driven body to be moved relative to each other by vibration excited in the vibrating body, and a lens barrel, an image pickup apparatus, and a stage device each provided with the vibration drive device.
Description of the Related Art
There has been known a vibration drive device that brings a driven body into pressure contact with a vibrating body formed by joining an electromechanical energy conversion element to an elastic body and excites a predetermined vibration in the vibrating body by applying an alternating current (AC) signal to the electromechanical energy conversion element, to thereby move the vibrating body and the driven body relative to each other. For example, there has been known a vibrating body that has a piezoelectric element, which is an electromechanical energy conversion element, bonded onto a first surface of a plate-shaped elastic body, and two protrusions formed on a second surface of the elastic body opposite from the first surface, with a predetermined spacing therebetween. In this vibrating body, each of the protrusions is caused to perform elliptic motion in a plane including a direction connecting between the two protrusions and a direction of thickness of the elastic body, and the driven body is brought into pressure contact with the tops of the respective protrusions, whereby the driven body is driven in the direction connecting between the two protrusions as a driving direction.
Further, as a vibration drive device using a vibrating body of the above-described type, there has been proposed one which has a single or a plurality of vibrating bodies disposed on an annular support base such that a driving direction coincides with a tangent direction, and is configured to bring an annular driven body into pressure contact with the one or plurality of vibrating bodies to thereby drivingly rotate the driven body (see Japanese Patent Laid-Open Publication No. 2012-5309).
In the vibration drive device using the above-described vibrating body or bodies, however, when an external force such as drop impact is applied to any vibrating body, a pressure application force acting between the vibrating body and the driven body increases to largely bend the vibrating body, which can cause undesired separation between the elastic body and the piezoelectric element bonded thereto.